Here's a cleaned-up version of the wip/elucidator-integration branch...

Here's what I was going for:

* Remove redundant `receive` methods: All of these actors get some kind of scoped query
* The `ClientHandler` deals with **all** query deserialization is done (and only done) at the ClientHandler layer.

Next steps: result serialization needs to be done either at the
ClientHandler layer, or some actor responsible for converting results
into JSON.  The principle being: most of the actors that do query lookup
and processing should know NOTHING about web or web-socket requests and
clients that want JSON.
Merge pull request #233 from typesafehub/wip/elucidator-integration-cleanup

Here's a cleaned-up version of the wip/elucidator-integration branch...